The Senate is expected to vote Thursday on whether to confirm Mari Carmen Aponte as ambassador to El Salvador. Democrats are attempting to overcome a Republican filibuster blocking the nomination in what has turned into a fight aimed at Latino voters in the swing state of Florida.

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Senate Democrats are making a second attempt to overcome a Republican filibuster that's blocking the Obama administration's choice for ambassador to El Salvador. The Senate is expected to vote today on whether to confirm Mari Carmen Aponte. Thanks to election year politics, that confirmation fight has turned into a drama aimed squarely at Latino voters in the swing state of Florida. NPR's Tamara Keith reports.

TAMARA KEITH, BYLINE: Marco Rubio, Florida's Republican senator, is often mentioned as a potential candidate for vice president. And in the case of Mari Carmen Aponte's confirmation fight, he's become a focal point. Zuraya Tapia from the Hispanic National Bar Association says that's because Rubio initially voted to block Aponte's nomination back in December. And she says other senators followed his lead.

ZURAYA TAPIA: Had his support been expressed fully and had he actively supported Mari Carmen back in December, she would have, we believe, certainly cleared a Senate confirmation.

KEITH: Rubio says he never opposed Aponte on personal grounds. He had a larger beef with the Obama administration over its policies in the Western Hemisphere, particularly related to Nicaragua.

SENATOR MARCO RUBIO: I opposed every Western Hemispheric nominee until the administration did a few things I asked of them. And they did those things, and so I did what I told them I would do.

KEITH: Rubio agreed to change his no vote to a yes and to round up enough other GOP votes to move her nomination. And this is where the story gets messy. Rubio says he did this in December, before the holiday recess. Democratic aides say his list of Republican votes came too late, and wasn't solid. Senate Majority Leader Harry Reid didn't schedule the vote. Aponte, who had been serving as ambassador to El Salvador in an interim role, came home.

Now the Hispanic National Bar Association, the Florida Democratic Party and others are making the case that if today's expected vote comes up short, it's on Rubio's head. The senator isn't interested in taking the blame.

RUBIO: The bottom line is the votes were there in December. Harry Reid knew it. He decided not to vote on it because he wanted to use it for politics. That's what these guys do. And at the end of the day, the victim is not just the U.S.'s mission in El Salvador, but Mari Carmen.

KEITH: Rubio says he plans to vote yes, and if others want to follow his lead, great.

Now, you might be asking: Why now, and why all this focus on Rubio? Ana Navarro, a Republican strategist in Florida who goes way back with Rubio, has an idea.

ANA NAVARRO: He's not the one holding up the vote. And I would argue that perhaps there is some pre-emptive political attack against a guy who's being mentioned as a potential VP nominee on a Romney ticket.

KEITH: Romney, Rubio and President Obama will all be in Orlando next week for a conference of Latino leaders. And their messages will be aimed at the broader Latino community in Florida. Aponte is a high-profile Puerto Rican. In Central Florida, Puerto Ricans are coveted swing voters, says Rafael Fantauzzi, president of the National Puerto Rican Coalition.

RAFAEL FANTAUZZI: Nobody should assume that Puerto Ricans in Florida are Democrats or Republicans or independents. I actually think that they - and, you know, it's a vote that is up for grabs for anybody that has a compelling message.

KEITH: And depending on how the Aponte vote turns out, it could easily become fodder in a micro-targeted campaign message aimed at Puerto Rican voters.

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